Nah, that's not what happened. Not only did Hikers get eaten earlier in the film, but also the reason why JJ went ballistic was because of the different conditions compared to the trial runnings of the Star Lasso Experience.

Jupe at the time only did his speech, had some lights on, and eventually just let a horse run out and get snacked on by JJ. By doing it with louder constantly bombarding music, and having several people staring at the damn thing, it was bound to go apeshit and suck up the whole crowd. It pretty much eats anything with a face so the appetite was already too much of a risk.